1. Field of the Invention
The present general inventive concept relates to a hard disk drive, and more particularly, to an actuator apparatus used with a hard disk drive having a structure to reduce noise and an impulse occurring by contact of an actuator and a stopper when a magnetic head is unloaded.
2. Description of the Related Art
An HDD (hard disk drive) is an example of an auxiliary memory device used in a computer, which reproduces data from a disk or records data onto a disk using a magnetic head.
FIG. 1 is a plan view schematically illustrating a conventional HDD, and FIG. 2 is an enlarged plan view illustrating a voice coil motor portion of a conventional actuator apparatus for the HDD of FIG. 2.
Referring to FIGS. 1 and 2, the HDD includes a magnetic disk (a hard disk) 3, that is, a recording medium for recording data, a spindle motor 2 positioned on a base member 1 for rotating the magnetic disk 3, and an actuator 10 having a magnetic head 14 for recording and reproducing data on and from the magnetic disk 3.
One or more disks spaced apart from each other at a predetermined interval are positioned so as to be rotated by the spindle motor 2. A ramp 5 is positioned outside the magnetic disk 3 for placing the magnetic head 14 thereon from the data recording surface of the magnetic disk 3 and safely holding the magnetic head 14 when the power is cut off.
The actuator 10 includes an actuator arm 11 positioned to pivot about a pivot shaft (not illustrated) positioned on the base member 1. The actuator arm 11 has a pivot hole 12 in its middle portion to be pivotably connected to the pivot shaft. The magnetic head 14 is positioned at one end, i.e., the front end, of the actuator arm 11, and an overmold 13 is coupled to the other end, i.e., the rear end, of the actuator arm 12, to be connected with a coil 15 of a voice coil motor (VCM). The actuator arm 11 is rotated by the VCM.
As described above, the VCM includes the coil 15 connected to the rear end of the actuator arm 11. A lower yoke 16 is positioned at a predetermined interval under the coil 15 and fixed to the base member 1. An upper yoke (not illustrated) is positioned over the coil 15 and connected to the lower yoke 16 by a screw. A magnet 17 is attached on the upper surface of the lower yoke 16 and spaced from the coil 15 at a predetermined interval.
In the conventional HDD having the aforementioned structure, a lift force by a rotation of the magnetic disk 3 acts on the magnetic head 14 during a data recording/reproducing operation. Accordingly, the magnetic head 14 is maintained in a floating state at a predetermined interval from the magnetic disk 3 due to the lift force, and records and reproduces data on and from the rotating magnetic disk 3 in this state.
When power is cut off and the disk 3 stops rotating, the lift force disappears. Before the lift force disappears, the magnetic head 14 moves from the data recording surface of the magnetic disk 3, thereby preventing any disk damage by a contact with the disk 3. That is, before the magnetic disk 3 stops rotating completely, when the actuator arm 11 is rotated by the VCM such that the magnetic head 14 moves over the ramp 5 outside the magnetic disk 3, the magnetic head 14 is safely held on the ramp 5 though the magnetic disk 3 stops rotating, thereby preventing damage to the disk 3.
When the power is turned on and the magnetic disk 3 starts rotating again, the lift force is generated again, and the magnetic head 14 moves above the magnetic disk 3 from the ramp 5 since the actuator arm 11 is rotated by the VCM. The magnetic head 14 moving onto the magnetic disk 3 floats from the surface of the magnetic disk 3 by the lift force generated by the rotation of the magnetic disk 3, and moves to a desired position by the pivot motion of the actuator arm 11. Thus, the magnetic head 14 records or reproduces data on or from the magnetic disk 3, as described above.
The HDD includes an actuator locking apparatus (not illustrated) for locking the actuator 10 not to pivot after the magnetic head 14 is safely held on the ramp 5 while positioned outside the surface area of the magnetic disk 3. The actuator locking apparatus prevents the magnetic head 14 from moving from the ramp 5 onto the magnetic disk 3 as the actuator 10 arbitrarily pivots by an external impact when power is off.
When the magnetic head 14 is safely held on the ramp 5, the overmold 13 coupled to the rear end of the actuator arm 11 comes into contact with a stopper 20 positioned at the lower yoke 16, so that the magnetic head 14 does not leave the ramp 5.
Below, the structure of the aforementioned conventional actuator apparatus and its problems will be described.
FIG. 3 is a plan view of a VCM portion illustrating the conventional actuator apparatus. FIG. 3 illustrates the position of the actuator arm 11 without the stopper 20.
Referring to FIGS. 1 through 3, the stopper 20 is positioned in the lower yoke 16 forming the VCM, a retract pin 19 including a magnetic substance is positioned in the overmold 13 of the actuator arm 11, and a protrusion region 18 for interacting with the retract pin 19 is formed on the magnet 17 forming the VCM. A magnetic force generated by a leakage magnetic flux from the protrusion region 18 of the magnet 17 acts on the retract pin 19 positioned in the actuator arm 11, thereby generating a torque that rotates the actuator arm 11 clockwise and counter-clockwise about the pivot shaft.
When there is no command from a host for predetermined period of time, when a serious danger occurs when operating a disk drive, or when the power is cut off, the HDD moves the magnetic head 14 to the ramp 5 such that the magnetic head 14 is secured on the ramp 5, thereby preventing the magnetic head 14 from any damage caused by colliding with the magnetic disk 3. In the conventional actuator 10, in order to prevent the magnetic head 14 from breaking from the ramp 5 after the magnetic head 14 is secured on the ramp 5, the overmold 13 of the actuator arm 11 contacts the stopper 20 positioned in the lower yoke 16. That is, while the overmold 13 of the actuator arm 11 is in contact with the stopper 20 positioned in the lower yoke 16, the clockwise torque continuously acts on the actuator arm 11. FIG. 3 illustrates the position of the actuator arm 11 without the stopper 20, where the torque generated by the retract pin 19 and the protrusion region 18 of the magnet 17 is 0. In this position, regardless of the direction in which the actuator arm 11 rotates, the torque is generated in the opposite direction to the rotation direction of the actuator arm 11, and thus the actuator arm 11 returns to its original position.
In the conventional actuator 10 having the aforementioned structure, when the magnetic head 14 is unloaded, that is, the magnetic head 14 is parked on the ramp 5, the clockwise torque generated by the retract pin 19 and the protrusion region 18 of the magnet 17 is added to the clockwise torque of the actuator arm 11 in the VCM. Thus, the overmold 13 of the actuator arm 11 collides hard with the stopper 20.
In this case, noise is generated and an impact force acts on the magnetic head 14, thereby affecting the performance of the magnetic head 14.
The noise and impact experienced during the collision of the overmold 13 and the stopper 20 when the magnetic head 14 of the actuator 10 is parked on the ramp 5 have a bad influence upon the actuator 10, thereby affecting the performance of a disk drive and the working conditions of a user.